The El Royale is based on the famous Cal Neva Resort and Casino that was once owned by Frank Sinatra.

Assuming the Richard Nixon press conference shown on TV is happening live (or earlier that day), the film takes place on Jan. 27, 1969.

The El Royale was built from scratch on a soundstage with much of the furniture and decor being custom made (including branded matchboxes and coasters for the bar). The colour-scheme was meticulously set out so that the California side was mostly yellows and oranges, while the Nevada side was purples and blues. Red was reserved for the borderline, jukebox, and chandelier, while green is almost entirely absent until the end.

Chris Hemsworth had to lose 25-30 lbs of muscle weight immediately after Avengers: Infinity War (2018) wrapped to star in this film.

Shot on actual film without traditional set-lighting. The hotel was designed to allow enough light to shoot by.

Drew Goddard's process of selling the script was under heavy secrecy, only sending it to top studio execs. Potential buyers had to read it on a tablet and then return it when finished.

There was no pre-recorded soundtrack so all of Cynthia Erivo's singing in the film is for real. For the lengthy tracking shot scene behind the hotel mirrors, Erivo had to perform "Try a Little Tenderness" 27 times.

Tom Holland was offered the role of Miles Miller, but turned it down.

Russell Crowe was originally cast in a role. He eventually dropped out and was replaced by Jon Hamm.

All the cast - and writer-director Drew Goddard - took a pay cut in order to get the film made.

Two songs by The Crystals figure prominently in association with the character Darlene Sweet. The character is shown to be a studio singer backing on a recording of "He's a Rebel". Later at the jukebox she selects "He's Sure the Boy I Love". It is notable that both are singles by the band in which real-life singer Darlene Love sang lead.

Jeff Bridges was Drew Goddard's first choice for the part of Father Flynn. Bridges readily agreed to take on the role after reading the script.

In the movie it's called El Royale Hotel. In actuality it's both a "motel" and a hotel. Hotel rooms are accessible through an internal hallway. Motel rooms are accessible from the outside.

Drew Goddard worked on the script for two years.

Matthew McConaughey was considered for the role of Billy Lee.

This is the second collaboration between Drew Goddard and Chris Hemsworth since The Cabin in the Woods (2011).

Darlene Sweet drives a 1950 Studebaker Commander (4-door). Emily Summerspring drives a 1969 Mercury Cougar Eliminator.

Beyoncé was originally considered for the role of the African-American singer that later went to Cynthia Erivo.

Drew Goddard wrote the script on spec. After a bidding war, 20th Century Fox secured the rights to it.

"Flynn" was also Jeff Bridges's character's name in TRON (1982).

Released the same day as First Man (2018), another period piece set in 1969, shot on film, with Shea Whigham in the cast.

The Crystals' "He Sure The Boy I Love" from 1962 never got a release on 78rpm record format, yet it is shown playing on the Wurlitzer 78 jukebox.

Nick Offerman and Jim O'Heir previously worked together on Parks and Recreation (2009). Jon Hamm also guest-starred on the show.

The film had its world premiere at Fantastic Fest on September 27, 2018, and also screened at the San Sebastián International Film Festival.

Chris Hemsworth and Jeff Bridges have both appeared in the Marvel Cinematic Universe. Hemsworth played the protagonist Thor and Bridges played the antagonist Obadiah Stane/Iron Monger. In this film, Bridges is the protagonist and Hemsworth is the antagonist.

When given a choice of red or black at the roulette wheel, Dakota Johnson's character, Emily, chooses red. 'Red' was the safe word for Johnson's character Anastasia in the film Fifty Shades of Grey (2015).

Katharine Isabelle has one line and appears in the movie for a brief moment as Miles's Auntie Ruth.

Darlene Sweet is a thinly veiled reference to singer/actress Darlene Love.

Chris Hemsworth's character, Billy Lee, is loosely based on Charles Manson. The horrifying murders that Rosie is hinted to have committed reference to the Tate murders carried out by the Manson Family. Another unsettling connection between Billy Lee and the Manson Family/Tate murders is the song used to officially introduce him in the story: "Twelve Thirty (Young Girls Are Coming to the Canyon)" by The Mamas and the Papas. Apparently, when the bodies of Sharon Tate and her friends were found in the Cielo Drive house, the song was heard playing in another room.

The hidden roll of film is said to show an affair of a well respected dead senator. As the movie takes place in 1969 it is most likely in reference to Bobby Kennedy (Robert F. Kennedy), who was assassinated in 1968. Speculation of John F. Kennedy and Martin Luther King Jr. are also possible, however JFK died in 1963 during the hotel's prime and MLK's love affairs had already been taped by the FBI, and the film was shot one year prior to the events depicted in the movie.

During the heist, Dock mentions meeting Felix in Rocklin. That city is a suburb of Sacramento and is on the most direct route from Stockton, where the robbery takes place, to Cal-Neva, the real life inspiration for the El Royale.

The other crooks call Donald O'Kelly "Doc" or "Dock" because of his initials - D.O'K.

The El Royale Hotel can also be an allegory for Limbo, a place between Heaven and Hell where lost souls travel awaiting judgement. Viewers can interpret for themselves if California or Nevada fall under Heaven or Hell.

Coincidentally both this film and Once Upon a Time... in Hollywood (2019) feature the songs 'Hush' by Deep Purple and 'Twelve-Thirty' by The Mamas and the Papas, are set in 1969, and reference the Manson family.